A cable is loaded with three concentrated loads P = 16 k at quarter spans (i.e., L/4, L/2, and 3L/4 from the left end), and L = 40 ft is the total span between the supports. The resulting sag of the cable is 3 ft at L/4 and 3L/4, and 4 ft at L/2. The horizontal thrust at the cable supports equals: A. 320 k B. 160 k C. 80 k D. 240 k E. None of the above